An Experimental

1
An Experimental .NET Operating System
Based on
the CLI
Theme Workshop 2006 - Microsoft Research Asia

• An executing method of a OS kernel represented in
  the CIL

Research Division in Engineering, Musashi
Institute of TechnologyAkio TAKAHASHI Graduate
School of Systems and Information Engineering
University of TsukubaKazuhiko KATO
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Introduction

• We developed a new CLI (.NET)-based operating
  system.
• CLI is used in two ways
• The OS is implemented with CLI.
• Application programs run on CLI.
• The OS is mostly written in C.
• Type safety
• Memory safety

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Backgrounds

• CLI provides enough specs that system software
  should have.
• Effective speed
• Security
• However, CLI has not been applied to operating
  systems.
• Conventional OSs cannot fully take advantage of
  CLI.
• To use CLI for OS description, we have to develop
  a technique to handle CLI intermediate codes for
  OS kernel execution.
• CLI languages are usually compiled into a
  intermediate code,the CIL (Common Intermediate
  Language).

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Related Work

• Java-based
• JavaOS (Sun Microsystems)
• JX (OSS)
• JNode (OSS)
• CLI-based
• Singularity (Microsoft Research)

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Basic Architecture

• (4 slides)

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Approaches

• Utilize CLI features as much as possible.
• At runtime, all the system objects are expressed
  in CLI.
• Take advantage of existing software
• Mono Class Library (as .NET standard library)
• The FreeType font engine

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System Structure

• Legacy Kernel
• Functions
• Memory manager Device drivers
• CIL interpreter
• Written in C and compiled into native codes in
  advance.
• Used only in the bootstrap time it disappears
  after that.
• Managed Kernel
• Functions
• Ordinary OS functions
• CIL compiler
• Mostly written in C and compiled into CIL codes
  in advance.
• At the bootstrap time, the CIL codes are compiled
  into native codes by the (self) CIL compiler by
  using the CIL interpreter in Legacy Kernel.

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Bootstrap Sequence
(disappear)

• Finally, only CIL programs remains in the system.

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Advantages of the Proposed Method

• The entire system can be expressed in CLI.
• We can fully take advantage of CLI technologies
  even in the earlier stages.
• Both native and CLI codes can be executed in a
  mixed manner.
• Mono Class Library is used with trivial
  modifications.
• High portability
• Architecture-dependent part is well modularized.
• We dont use MMU.

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Experiments and Demo

• (5 slides)

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Demo

• Run our OS with Text-mode on VMware
• It takes about 3 minutes to bootstrap and show
  the prompt.
• What you see on bootstrapping is
• Legacy Kernels Loading (with NO outputs)
• Compiling a little part (not complete)
• Managed Kernels Loading some data (with many
  outputs)
• What I do is
• Execute a ls program for listing the contents
  of CD-ROM
• Execute a cat program for its source file

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Start-up Screens

• Figures are taken just after OS booted.
• Text Mode (Left)Graphic Mode (Right)

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Fundamental Test

• The simple ls program (ls.cs).
• Compile ls.cs on Windows
• Run ls.exe on Windows
• Copy ls.exe to our OSAnd run also
• We confirmed successful execution
• Cross-platform execution
• File system compatibility

• using System
• using System.IO
• class ls
• static void Main(string args)
• DirectoryInfo dir
• if(args.Length0)
• dir new DirectoryInfo(
• Directory.GetCurrentDirectory())
• else
• dir new DirectoryInfo(args0)
• foreach(FileSystemInfo fsi in dir.GetFileSystemIn
  fos())
• Console.Write("0,-32 ", fsi.Name)
• if(fsi is FileInfo)
• FileInfo fi (FileInfo)fsi Console.Write("0,
  10 B", fi.Length)
• else
• Console.Write("0,10 -","")

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Practical Test using Font Engine

• In both Windows and our OS, the FreeType Library
  can be successfully executed.
• FreeType is a high-quality font rendering engine
  written in C.
• Japanese characters are handled.

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Writing Device Drivers

• A constructor and a initializing method of DMA
  Controller class
• In the constructor, associative IOPort instances
  are created.
• In the initializing method, the device is
  controlled via associative I/O ports.

• private DMAController(
• ushort cadr0, ushort cadr1, ushort cadr2, ushort
  cadr3,
• ushort ccnt0, ushort ccnt1, ushort ccnt2, ushort
  ccnt3,
• ushort psts, ushort pcmd, ushort preq, ushort
  psmask,
• ushort pmode, ushort pcbpf, ushort ptmp, ushort
  pmclr,
• ushort pcmask, ushort pamask)
• this.cur_address0 new IOPort1(cadr0)
• this.cur_address1 new IOPort1(cadr1)
• this.cur_address2 new IOPort1(cadr2)
• this.cur_address3 new IOPort1(cadr3)
• this.cur_counter0 new IOPort1(ccnt0)
• this.cur_counter1 new IOPort1(ccnt1)
• this.cur_counter2 new IOPort1(ccnt2)
• this.cur_counter3 new IOPort1(ccnt3)
• this.status new IOPort1(psts)
• this.command new IOPort1(pcmd)
• this.request new IOPort1(preq)
• this.single_mask new IOPort1(psmask)

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Conclusion

• We designed and implemented a 100-pure CLI OS.
• Existing large-scale CLI libraries are executed
  with trivial modification.
• Mono Class Library
• FreeType font engine
• Device drivers are written in C.
• DMA Controller ATA/ATAPI CD-ROM device driver
• ISO9660 (CD-ROM file system) driver

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Future work

• Remove dependencies on the CIL interpreter to
  execute a few runtime methods.
• This requires analysis of the call-graphs of the
  runtime methods.
• Pre-execute the CIL interpreter in Legacy Kernel
  to generate a ready-made image of Managed Kernel,
  to shorten the start up time.

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Acknowledgements

• This research project was supported by Mitou
  Software Development Program of
  Information-technology Promotion Agency (IPA),
  Japan.
• We thank to Dr. Dave Provert for useful comments.

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• Does anyone have any questions?